Field surveys were conducted in Core and Back Sounds, North Carolina. USA, to relate the physical setting of seagrass beds, as measured by a wave exposure index (REI), tidal current speed and water depth, to various measures of the sedimentary environment, spatial heterogeneity of seagrass distribution and measures of seagrass abundance. Seagrass beds in this area form patterns ranging from continuous to semi-continuous to widely dispersed, discrete patches across a gradient of increasing hydrodynamic activity. Tidal current speeds, exposure to waves and relative water depths revealed strong correlative evidence that physical processes influenced landscape-scale (50 X 50 m range with 1 m resolution) features of seagrass beds. Some habitat attributes, such as percent cover of seagrasses, seagrass bed perimeter to area ratio, sediment organic content and percent silt-cldy, declined with increasing REJ and current speed. Increased aggregation of these data was observed above and below the 50% seagrass cover value, and, supported by principle components analysis, signaled an abrupt transition of environmental setting correlated with this coverage level. The 50% cover value also occurred at current speeds of -25 cm S-', which should be near the initiation of motion current speed for local sand sediments, and an RE1 of -3 X 10h This coverage is also near to the 59.28% coverage value, previously determined to be where landscape elements join and below which they tend to exist as discrete patches. We hypothesize that a rapid loss of seagrass habitat structural integrity may occur as the habitat fragments, and seagrass landscape elements become isolated, contributing to the observed transition and accompanying data aggregation above and below the -50% coverage level. We discuss the interaction of physical setting, disturbance, landscape contiguity and growth response by these modular plants in the production of the observed landscape patterns across these hydrodynamic gradients.

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Global seagrass habitats are threatened by multiple anthropogenic factors. Effective management of seagrasses requires information on the relative impacts of threats; however, this information is rarely available. Our goal was to use the knowledge of experts to assess the relative impacts of anthropogenic activities in six global seagrass bioregions. The activities that threaten seagrasses were identified at an international seagrass workshop and followed with a web-based survey to collect seagrass vulnerability information. There was a global consensus that urban/industrial runoff, urban/port infrastructure development, agricultural runoff and dredging had the greatest impact on seagrasses, though the order of relative impacts varied by bioregion. These activities are largely terrestrially based, highlighting the need for marine planning initiatives to be co-ordinated with adjacent watershed planning. Sea level rise and increases in the severity of cyclones were ranked highest relative to other climate change related activities, but overall the five climate change activities were ranked low and experts were uncertain of their effects on seagrasses. The experts' preferred mechanism of delivering management outcomes were processes such as policy development, planning and consultation rather than prescriptive management tools. Our approach to collecting expert opinion provides the required data to prioritize seagrass management actions at bioregional scales.

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Landscape ecology focuses on questions typically addressed over broad spatial scales. A landscape approach embraces spatial heterogeneity, consisting of a number of ecosystems and/or landscape structures of different types, as a central theme. Such studies may aid restoration efforts in a variety of ways, including (1) provision of better guidance for selecting reference sites and establishing project goals and (2) suggestions for appropriate spatial configurations of restored elements to facilitate recruitment of flora/fauna. Likewise, restoration efforts may assist landscape–level studies, given that restored habitats, possessing various patch arrangements or being established among landscapes of varying diversity and conditions of human alteration, can provide extraordinary opportunities for experimentation over a large spatial scale. Restoration studies can facilitate the rate of information gathering for expected changes in natural landscapes for which introduction of landscape elements may be relatively slow. Moreover, data collected from restoration studies can assist in validation of dynamic models of current interest in landscape ecology. We suggest that restoration and landscape ecology have an unexplored mutualistic relationship that could enhance research and application of both disciplines.